The most common and most likely answer to this crossword clue is the 7 letter word DEFAULT
I've seen this crossword clue in Financial Times
D
E
F
A
U
L
T
Buddy explains!
The straight part
We know that "fail to pay" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fail to pay = default.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does DEFAULT mean?
DEFAULT noun- The condition of failing to meet an obligation.
- The original software programming settings as set by the factory
- A loss incurred by failing to compete.
- A selection made in the absence of an alternative.
- A value used when none has been given; a tentative value or standard that is presumed.
- The failure of a defendant to appear and answer a summons and complaint.
- A failing or failure; omission of that which ought to be done; neglect to do what duty or law requires.
- Lack; absence.
- Fault; offence; wrong act.
- To fail to meet an obligation.
- To lose a competition by failing to compete.
- To assume a value when none was given; to presume a tentative value or standard.
- To fail to appear and answer a summons and complaint.